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LTC4414 Recommended for New Designs
The LTC4414 controls an external P-channel MOSFET to create a near ideal diode function for power switchover. This permits highly efficient OR’ing of...
Datasheet
LTC4414 on Analog.com

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LTC4414 failiures

		
	
				

			

									
					    AElb
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Jul 9, 2024 
				
			
			
		

		
		                     
				
        		

		    
		    		    

		      		            		        
Category: Hardware

    		        		            		    
Product Number:  LTC4414  

    		        		    		    

		    		    
		    			

			    
Hi,


I am using LTC4414 as on Figure 7 at the datasheet with the following changes:


1. Sense pin is connected to the outPut ( not to GND).


2. Additional P-FET in parallel the the first P-FET.


3. Cout is 100nF.


See drawing below:


 




In our design, some of the units after working well for a while, stoped working  (Gate didn't get down). and  IC become worm a bit.


 


We are working with battery alone as the supply input and having 40uF capacitance at the input.


We planed to use this part for delivering up to 10A current but at the test we perform we used only 3-4A.


 


Can you suggest the reason for this faliure.


 


Thanks and Best regards,


Aharon


 

			

			
									
		                             
                        

    

                                            
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    •  Analog Employees  
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                on Jul 9, 2024 3:24 PM
            
            
						
			            		
    
		
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    In figure 7, SENSE is connected to ground to fully enhance the PFET when CTL goes high.
     
    

    You have SENSE connected it to VOUT, which is only useful in a diode configuration (LTC4414 regulates VFWD to block reverse current).

    Try connecting SENSE to ground.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
				
				
				
		
		
    
			
		
    
	
    

    

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                on Jul 9, 2024 5:34 PM
            
            
						
			            		
    
		
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    Thanks for your answer.
    

    The failure don't happen to all device but just in some of them? Do you think it can be the reason?
    

    It is very difficult to reproduce problem...but apparently it happen randomly. This is the reason that even if I will connect Sense to GND., I will not known if it fixed the problem.
    

    BTW, what about the parallel PFET connection. Is it OK?
    

    Thanks
    

    Aharon 
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
				
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
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                on Jul 9, 2024 11:08 PM
            
            
												
						in reply to AElb
					
										
			            		
    
		
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    AElb said:
    The failure don't happen to all device but just in some of them? Do you think it can be the reason?
    

    Maybe. Could be an safe operating area (SOA) issue if COUT is big and the load is connecting during start-up.
    

    AElb said:
    BTW, what about the parallel PFET connection. Is it OK?
    

    Paralleling FETs is okay, but if you want to increase current handling, why not just switch to an NFET controller?
    You'll get the ability to control inrush current into COUT during start-up, which would address an SOA issue.
    Look into the LTC4365 and LTC7004.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
				
				
				
		
		
    
			
		
    
	
    

    

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